Project Summary Peripheral nerves serve as a bidirectional link between the central nervous system (CNS) and its distal targets. The autonomic nervous system (ANS), which is part of the peripheral nervous system, innervates internal organs to modulate their function and transmits sensory information back to the CNS. By selectively stimulating the ANS nerves, neuromodulation of target organs can be achieved. Numerous therapeutic applications of neuromodulation are currently under investigation to relieve diseases and conditions. In-depth knowledge of neuroanatomy and real-time information on nerve health during surgical or neuromodulation procedures are essential for successful outcomes. The current method for mapping neuroanatomy and evaluating nerve injury is end-point histology, which is limited by difficulty in obtaining temporal biological responses absent subject variability, processing artifacts, and the lag between overstimulation and injury manifestation. Thus, it is imperative to develop real-time quantitative imaging tools to assess nerve structure and function. The goal of this project is to develop optical coherence tomography (OCT) based peripheral nerve imaging technology to study the structure and function of somatic and autonomic nerves. We will use specific advantages of OCT, particularly the ability to derive intrinsic contrast measures and its depth sectioning capability, to validate novel tools for mapping peripheral nerve anatomy and define new imaging biomarkers of neuromodulation and nerve injury. We will deploy OCT systems to SPARC investigators to expand the potential nerve applications that benefit from our tools. A successful effort will transform the manner in which neuromodulation devices are assessed and deployed, leading to more effective therapies and better patient outcomes.